Bumped most framework code to Java 7.

Fixed a bug related to type inference.  Fixed Java 7 bugs.

Polyglot can compile itself in Java 7.
More conversion to Java 7.

Updated JFlex to version 1.5.1.

Fixed a reflection bug in SerialVersionUID.
Changed file permissions.
AmbTypeNode now extends AmbQualifierNode.
Merge branch 'NoDelFactory' of https://github.com/polyglot-compiler/polyglot into NoDelFactory
Removed redundant Ambiguous from AmbTypeNode's explicit super-interfaces.